Institut für Spezielle Botanik, Universität Mainz, D-55099 Mainz, Germany;
Am J Bot. 2001 Mar;88(3):486-98.
Melastomataceae are among the most abundant and diversified groups of plants throughout the tropics, but their intrafamily relationships and morphological evolution are poorly understood. Here we report the results of parsimony and maximum likelihood (ML) analyses of cpDNA sequences from the rbcL and ndhF genes and the rpl16 intron, generated for eight outgroups (Crypteroniaceae, Alzateaceae, Rhynchocalycaceae, Oliniaceae, Penaeaceae, Myrtaceae, and Onagraceae) and 54 species of melastomes. The sample represents 42 of the family's currently recognized ∼150 genera, the 13 traditional tribes, and the three subfamilies, Astronioideae, Melastomatoideae, and Memecyloideae (= Memecylaceae DC.). Parsimony and ML yield congruent topologies that place Memecylaceae as sister to Melastomataceae. Pternandra, a Southeast Asian genus of 15 species of which five were sampled, is the first- branching Melastomataceae. This placement has low bootstrap support (72%), but agrees with morphological treatments that placed Pternandra in Melastomatacaeae because of its acrodromal leaf venation, usually ranked as a tribe or subfamily. The interxylary phloem islands found in Memecylaceae and Pternandra, but not most other Melastomataceae, likely evolved in parallel because Pternandra resembles Melastomataceae in its other wood characters. A newly discovered plesiomorphic character in Pternandra, also present in Memecylaceae, is a fibrous anther endothecium. Higher Melastomataceae lack an endothecium as do the closest relatives of Melastomataceae and Memecylaceae. The next deepest split is between Astronieae, with anthers opening by slits, and all remaining Melastomataceae, which have anthers opening by pores. Within the latter, several generic groups, corresponding to traditional tribes, receive solid statistical support, but relationships among them, with one exception, are different from anything predicted on the basis of morphological data. Thus, Miconieae and Merianieae are sister groups, and both are sister to a trichotomy of Bertolonieae, Microlicieae + Melastomeae, and Dissochaeteae + Blakeeae. Sonerileae/Oxysporeae are nested within Dissochaeteae, Rhexieae within Melastomeae, and African and Asian Melastomeae within neotropical Melastomeae. These findings have profound implications for our understanding of melastome morphological evolution (and biogeography), implying, for example, that berries evolved from capsules minimally four times, stamen connectives went from dorsally enlarged to basal/ventrally enlarged, and loss of an endothecium preceded poricidal dehiscence.
野牡丹科是热带地区最为丰富多样的植物类群之一，但科内的系统发育关系和形态演化仍不清楚。本研究采用最大简约法和最大似然法对来自 8 个外类群（铁青树科、野牡丹科、褶叶花科、铁青树科、使君子科、桃金娘科和柳叶菜科）和 54 种野牡丹科植物的 rbcL 和 ndhF 基因及 rpl16 内含子的 cpDNA 序列进行了分析。该样本代表了野牡丹科目前公认的约 150 个属中的 42 个，13 个传统的族，以及三个亚科，即 Asteronioideae、Melastomatoideae 和 Memecyloideae（= Memecylaceae DC.）。简约法和最大似然法得出的拓扑结构一致，将 Memecylaceae 置于野牡丹科的姐妹群位置。Pternandra 是东南亚的一个属，有 15 个种，其中 5 个种被采样，是野牡丹科中最早分支的科。这种关系的支持度较低（72%），但与形态学处理结果一致，因为 Pternandra 的叶具互生叶脉，通常被归为一个族或亚科。在 Memecylaceae 和 Pternandra 中发现的隔层韧皮部岛，而在大多数其他野牡丹科中没有发现，可能是平行进化的结果，因为 Pternandra 在其他木材特征上与野牡丹科相似。在 Pternandra 中发现的一个新的原始特征，也存在于 Memecylaceae 中，是纤维状的花药内皮。较高的野牡丹科植物没有内皮，而与野牡丹科和 Memecylaceae 关系最近的类群也没有内皮。其次，深裂的是 Astronieae，花药以裂缝开裂，而其余的野牡丹科则以孔开裂。在后者中，几个与传统族相对应的属群得到了坚实的统计支持，但它们之间的关系，除了一个例外，与基于形态学数据预测的结果不同。因此，Miconieae 和 Merianieae 是姐妹群，它们与 Bertolonieae、Microlicieae + Melastomeae 和 Dissochaeteae + Blakeeae 的三分叉关系是姐妹关系。Sonerileae/Oxysporeae 嵌套在 Dissochaeteae 中，Rhexieae 在 Melastomeae 中，非洲和亚洲的 Melastomeae 在新热带的 Melastomeae 中。这些发现对我们理解野牡丹科的形态演化（和生物地理学）具有深远的意义，例如，浆果至少从蒴果进化而来 4 次，药隔连接从背侧扩大到基/腹侧扩大，以及内皮的缺失先于孔裂开裂。
